Furnace grate



1932- A. w. BENNIS 1,883,110

FURNACE GRAI 'E Filed March 14, 1929 5 Sheets-Sheet 1 F EIW A. W. BENNISFURNACE GRATE Nov. 15, 1932.

Filed March 14, 1929 5 Sheets-Sheet vz/vroe agwzaam #rrai/ma A. W.BENNIS FURNACE GRATE Nov. 15, 1932.

5 Sheets-Sheet 3 Filed March 14. 1929 ATTORNEKS.

NOY.-

A w BENNIS FURNACE GRATE Filed March 14, 1929 S Sheet S-Sheet 4 FIQM. 56Fig.5.

ATTORNEYS.

A. W. BENNIS FURNACE GRATE Nov. 15, 1932.

Fild March 14, 1929 5 Sheets-Sheet 5 Patented Nov. 15, 1932.

UNITED STA j- '1,sss,110 l f ALFRED winmam BENNILS, on oLTon' nGLANnFURNACE GBATE' Application flIedMarc-h 14, 1929; Serial No. 347,068, andm Great-Britain March 14,1s2s

The present invention relates to furnace grates and more particularly ofthe chain grate type.

Under modern conditions of combustion,,

5 particularly with regardto electricity supplystation practice the useof heated air' for.

theair supply toithe furnace is demanded and as a consequence of thepassage of the heated air between the grate bars'or through said gratebars or their air spaces and also as a consequence of the hightemperature furnace conditionsabove the grate, theseare liable to becomeoverheated, causing them to deteriorate, crack and eventually burn away.a A fur l5 ther detrimental feature arises in that when the fire barsbecome heated in 'chain grates,

the fuel tends to when the bars which. produces a condition known ascauliflowering, with the result that the efliciency of combustion isimpaired and. the output is reduced with the result that the" furnacehas, to be slowed down and the grate cooled.

The tendency of modern conditions is to,

continually demand higher air temperature supply to the furnace, anditris extremely likely that as time goes on an air supply of evengreater temperature will be required.

With a view to meeting these-demands, the object of the presentinventionistoprovide means whereby links orfire bars of the V grate maybe kept cool independently of the temperature of the air supply throughthe grate so that while in use the dered substantially unburnable;

grate bars, a connection being formed be} tween the inlet of said airpassages" and a cool air chamber below the grate bars, whilst the exitof the air passage or passages is coning off the warm air from the warmair compartment. In the latter case, the warm air taken off may beutilized for combustion purposes. i

of the passages in the grate is ren- Accordingly to the presentinvention one or more an passages are provided in the;

r :scribe'd with reference to theaccompanying v In apreferredform ofconstruction, the. V 0

grate bars are mounted on hollow carrier bars which are divided into aplurality of compartments by. suitablediaphragms, or

division's. One Or more of these compartments is utilized for the transmssion ofcool air from'the source tOthB filI passages in the and thencetojthe'combustion chamber or further to air heaters to befurtherheated'and then utilized. forcombustion; v I Any suitable form ofconnection-may. be 7 I used between the grate bar'sian'd thecarrierbars. Preferably these connections. are in the form of tubes extendingbetween the ends graterbars and the orifices in the carrier ba l Theainmay be forced by a fan or the like means "through the 'cool aircompartments of the rhollow carrier bar and the'n through a the links orgrate bars'in parallel after which '75 it passes into the warm aircompartment in the, hollow carrier bars and thence onfto trunksorconduits toair'heaters after which it passes through said air heatersonto-hot" lair trunksto the underside-of the grateagain '80 where it'passes up to burn the fuel on the grate.

Trunks-or ,conduits' may be arran ged to conveythe coolrai-r tothemoving hollow carrier bars from the cool airysupplyf means, whilstadditional trunks areutilized to con- 'vey the heated air away from thehollow carrier bars. No mechanical difliculty exists in this transfer ofthe air from the'conduit to the hollow c arrier'b'ar'or from'the hollowcarrier bar to the trunk as .air has been 'fed totravelling chain gratecompartments in a number of ways in the past;

It will be obvious that the hollow carrier bars may have more than oneentrance forts.

drawings, in which-'1 mg air to the grate bars.

Figure 1 is a plan view of a general ar-g rangement of a grateconstructed according. to the present invention.

Figure2 is asectional elevation of the grate on the line BB of Fig. 1.

Figure 3 is a transverse section of the grate along the line A-A ofFig.2.

Figure 4 is a plan view on a larger scale, of a portion of the grate. I1

Figure 5 is an enlarged transverse section of the grate across a portionof this'only.

Figure 6 is a section through a portion of the longitudinal upper run ofthe grate.

Figure 7 is a transverse section of a por-;-

tion of a modified arrangement for supply- 7 F igure' 8 is a sectionalviewthrough. a

grate bar and hollow carrier bar on which said gratebar is mountedshowing one method-of interconnection between said grate bar and itscarrier bar for the purpose of allowing air to pass through the gratebar.

'Figures 9and 10 show modified forms of construction in which the gratebars are cast on tubes connected to the hollow carrier bars. Figures 11,12 and 13 aredetail views of a modified arrangement for the supply ofair to the grate bars, Fig. 11 being a transverse section throughthehollow carrier" bar, Fig. 12 being a corresponding lOIlgltllClll'lELlview in elevation and 13 beingacorrespond ing longitudinal view in plan.

Figures 14 and 15 show a modified arrangement for the air supply to thedrop link type of stoker, Fig. 14 being a transverse section across aportion of the upper run of the grate and Fig. 15 being a view inelevation over a portion of the longitudinal run of the grate. Figure 16is a perspective view showing the various parts diagrammatically intheir relationship to one another.

In the general arrangement as shown in Flgs. 1-3 of the drawings, theinlet ducts for supplying cool air forpassage through the grate'barsareillustrated at 20 and the exit ducts through whichthe' warm air isledaway,preferably to assist in the combustion onthe grate, are illustratedat 21, combustion air ducts being illustrated at 22.

It will be seen'from a study ofthese drawtending transversely over thewhole or a portion of the grate are shown at 25, whilst the rollers forsupporting the carrler bars are illustrated at 26 in Fig. 2.

' Turning to Figs. 4-6 0f the drawings it Wlll be seen that eachtransverse carrier'bar is formed with a pair of compartments 27, 28separated by a division wall or diaphragm 29.

A plurality of hollow grate bars 30 are mounted on each carrier bar.

rier bars are illustratedin Fig. 6. i p

YVith regard to the manner in which the extreme left hand grate bar ismounted on its carrier bar, it will be seen that a plurality of lugs 31are formed on the upper face of reach hollow carrier bar at spacedintervals along this, these lugs 31 being adapted to receive guides32,the lower portions of which are bifurcated to rest on such lugs 31whilst the upper portions of which are T- shaped to be engaged byT-shaped recesses in the grate bars. The grate bars are hollowasillustrated at 33, the passages through the grate bars being connectedto the chambers 27 and 28 of the hollow carrier bars so that cool airsupplied upwardly through the transverse cold airqduct 20. passes intothe longitudinally extendedportion of such duct 23 and thence intochambers 27 of all those carrier bars situated above said longitudinallyextended upper portion 23 of the cold air duct whereupon the cold airpasses through the grate bars on said carrier'bars and thence into the.warm aircompartment 28 of said carrier bars, whereupon the air whichhas been warmed in its passage through the grate bars is exhausted intothe longitudinally extended upper portion 24 of; the transverse warm'airduct 21. If desired, the'warm air is then led ofi-to air heaters forfurther heating and to subsequently assist in supporting combustion ofthe fuel on the grate.

'Any convenient arrangement may be adopted for mounting the grate barson to the transverse hollow carrier bars, A number of such arrangementsare illustrated in Figs. 8-13. I V

In the construction according to Fig. 8-the grate bars 34 have passages35 formed. therein, the inlet to -such passage 35-being connected to atube 36 whilst the exit of the passage '35 is. connected to the tube 37.

The tube 36 further is connected with a cool air compartment 38 of acarrier bar 39 whilst the tube 37 is connected to the warm aircompartment 40 of'said hollow carrier bar..

These tubes 36, 37 may either be cast'inlor otherwise suitably securedto the carrier bar 39 and the opposite ends inserted just within theinlet and exhaust ends respectively of the passages35', or alternativelysuch tubes may beca'st with such grate bars 34 and their ends inserted,priortofuse on the grate within the orifices formed in the upper face ofthe 1101- low carrier bar 39 V V In the modified form of constructionshown in. Fig. 9 a hollow carrier bar 41 is provided of substantiallytriangular cross section, the

Various methods'of mounting these grate bars on the carinto the warm aircompartment of such car-- rier bar. 7 Y 7 In the further modified formof construc tion illustrated in'Fig. 10 each grate bar48 is cast onatube 49,one end of whichtube-is insertedin the cool air compartment 50of the hollow carrier bar 51 whilst th eopposite end is inserted in thewarm air compartment52 of, such carrier bar. p H

It will be seen that in'the arrangements illustrated in Figs. 1-6 andFigs. 8-10, the

cool air passes from the cool air compartment of each carrier barthroughthe' grate bars mounted thereon in parallel andthen passes to'the warm air compartment of the carrier bar.

In the construction illustrated a Figs.

11-13 the cool 'air passes through a number of grate bars in seriesbefore returning to the;

warm air compartment ofthe lcarrier bar. By this, it is not meant toinfer that the 'air passes through every grate baron any single carrierbar in parallel prior toentering the warm air'compartment of suchcarrier bar. Preferably, separate streams'of cool air each 'pass throughabout six grate bars prior to entering the warm air compartment of thecarrier bar.

In Figs. 11-13 the carrier bar is illustrated at 51 and its cool andwarmair'compartments at 52 and 53 respect ively-whilst the grate barsmounted- .on the carrier bar are illustrated at The air passes along acoiled tube. in

series througha number of laterally adjacent grate bars 54,1'which areformed by casting the metal of the grate bars around, the tube.

In a further modified form of construction (not illustrated. in thedrawings) the tube itself may form the hollow grate'bar and for thispurpose, is'suitably shaped. and treated. It will be appreciated thatin: a very narrow grate one coil'ov'er each'carrier bar may besuflicientin which case it would not be necessary for thecarrierbarjtobe hollow, as means may be arranged at the inlet and outletoi' the coil to feed to and from the cool andvwarm air ducts. In wider-grates;;however, it would be preferred toprovide a'number of seriescoils, the number dependingon the coolness and speed of airpassing therethrough forcooling purposes.

In Figure 16, the ash pit 1O has'the grate above it, of which only theone carrie'rbar'25 opsuing-22 into the ash pit is shown, "with'the onegrate bar or link v thereon. The other figures of the drawings show thata lar e number of carrier bars, each with a great number "of gratebars30 may be employed. The carrier bar'is substantially oft-he form shownin Fig.8, with the central partition dividing it along its length into;compartments 38 and 40; Air pumped from compressor 11' by motonMpassesthr0ugh the cold air duct 20 into the-inlet trunk23 which .ifo'rmsa manifold, and hasan aperture in its upper surface. Thisaperture, itwill be un derstood, is norm'ally'closed by a plurality of tlie jbars25. In this conventional figure,'tl1e carrier bar 25'has been shown-awayfrom its definite position, for greaterclearnessr The .arrows indicatethefiow of coldair from-the 'coi'npressor 1 1-through"an openlnglt intothe compartment 3810f the carrier bar 25. Each of the grate bars 3O- hasa passage 32 through it by which airmay' pass from the coidi'air'compartment 38 intothe hot air compartmentAO. -A-t the other end oftheillustr ated carr er bar 25; -this hot'airpasses through the opening15 and an aperturein tliel'top outlet trunk or manifold 24 to the hotair duct-'21. Thencetlie air-moves through I an air heater 12shownconventionally as con 'nec'tedto the hot air pipe 18 leading to'the10-whence the air moves upward betweenthevariouscarrier bars 251 andgratebars 30 into the'ifire bed. 1 For the purpose of illustr'ating anarrange;

ment which maybeemployed for adapting Tthe present invention to the droplink type of stoker referencefis made to. Figs' 14 and 15 of thedrawings. In thesefigures the cold-air inlet is illustrated at 56 andthehot airexit" Cold air passes fronitheinle'toGupthrOugha'vert-icalconduit 58 and 'thenceoutwardly at 59' intopassages 60 formedin links 61{ The air 'is heated in its' travel along the passages thenceinto the hot airexit 57 (SQ-and returns to a verti'cal' conduit 62 andtween a plurality'of laterally adjacent links It will'thus be seenthatcoldair may bef ed f up through a verticalconduit situated be- I orgrate bars and "emerges from these links A or grate bars at the oppositeends thereof.

In this wayjasingle cold airinlet only is necessary for each pair oflaterally adjacent groupsiof. grate bars. In' the form ofjcon'structionFig. '7 a longitudinal cold'air duct 68 is pro vided as distinct fromthetransverse cold air ducts already de'scribed whilst'similar remarksapply to the longitudinalhot 'air ducts 64, these ducts 63 and' 6d beingconnected to vertical ductsor passages*65,i66' with the cold aircompartments and hotair com: I I "partm'ents respectively ofthevariouscarrier bars; 7

Incor'der to prevent the -h'ea'tedair which isjj fed tothe-furnace- 0r.cells under thegrate illustrated in.

from leaking into the cool air conduit grates, sliding joints or thelike, air at a higher pressure is utilized in the conduit to the coolair compartments in the hollow carrierbar thanis used under the grate. s

A number of cool air conduits may be utilized to feed cool air to thehollow carrier bars sothatsuch carrier bars may be fed with cool air atdifferent pressures according totheir position of travel along thefurnace.

It will be obvious that the means for 0001 ing the grate bars asdescribed above may be combined with the air supply regulating meansdescribed in the specifications accompanying my patent applicationsSerial Nos. 311,169, filed October 8,1928, and 334,772, filed January24, 1929. 1 v

I declare that whatI claim is n 1. A furnace grate comprising stationarylongitudinally directed and transversely spaced air inlet and outlettrunks having top apertures, hollow carrier bars operable to' travelover said trunks and to substantially close said apertures and havingbottom apertures positioned to register with theapertures of the trunks,hollow grate bars mounted on said carrier bars and communicatingtherewith so "that air may pass between the cavities of said grate andcarrier bars, means for supplying air to said inlet trunk, said inlet,trunk and carrier bars and grate bars providing passages for the airtherethrough to said outlet trunk, and means for withdrawing air fromsaid outlet trunk. I

2. A traveling furnace grate comprising hollow carrier bars and hollowgrate bars mounted thereon, each carrier bar containing a longitudinalpartition dividing it into two compartments, means "for placing thecavia: ties of the grate bars mounted on the carrier bars incommunication with each ofsaid compartments, and means for supplying airto one of said compartments, the other of said compartments having anoutlet.

3. A traveling furnacegrate comprising hollow carrier bars and hollowgra'tebars' mounted thereon, each said carrier bar con taining alongitudinal partitiondividing it into two compartments, an air inletconduit for delivering air into one compartment, an air outlet conduitfor permitting the escape of air from the' other compartment, and

means for placing the cavities of the grate bars mounted on the carrierbars in commu-' nication at theirends with an inlet and an outletcompartment of said carrier bars.

4:. A traveling furnace grate comprising hollow carrier bars andpluralities of hollow grate bars mounted thereon, conduit means forconnecting the grate bars of each pluralitv so'that the. air may flow insuccession through the bars of such plurality, each carrier barcontaining a longitudinal partition dividing 1t mto: two compartments,means for placing the cavity of the one end grate nasano bariof.eachplurality in communication with one said compartment and'the' cavityof the other end grate bar of each'plurality in com- I munication withthe othersaid compartment,

each said carrier bar and grate, wherebythe grate bars may be removedwithout disengagement of the carrler bars.

6.; A furnace-grate asin claim 2 in which the grate bars comprise-tubesand fuel supsporting structures formed upon the tubes,

and the ends of each tube being connected to a carrier bar whereby toestablish the com- :munication of thecavity of the tube with the twocompartments of thecarrier bar.

[71A furnace grate as in claim 2 in which the grate bars are providedwith tubes fixed thereto and extending relatively downwardly therefrom,vand hollow connecting means are provided on the grate bars for engagingsaid tubes whereby to form said communication means between the cavitiesin saidgrate bars and said carrier bars. v

8.,A; furnace grate comprising stationary air trunks extendinglengthwise of the grate and having apertures on their upper surfaces,hollow carrier barslocated above said air trunks and extendingtransversely; of the grateand having bottom apertures in communicationwith said trunks throughsaid trunk aperturesand providing airinlet andoutlet-7' compartments alternately extending transversely of the grate,a plurality of hollow grate bars mounted on said carrierbarsandincommunication at their ends with the air inlet and outletcompartments thereof,and

means for supplying air to one of said trunkswherefrom itmay'pass to theair inlet compartments, the other of said trunks having an outlet. 7 p pa p '9. A furnace grate comprising a plurality ofhollow carrier bars andmeans for con- 1 n'ecting the same to travel in chainto form a travelingfurnace grate structure, a plurality of hollowgratebars for formingthefuel supporting surface of thegrate mounted on each of saidcarrierbars,sai'd carrier bars extending transversely of the grate and beingprovided with lengthwise 'internal partitions dividing them each into?two compartments, each said hollow grate bar-having connections to each.of said compartments of the hollow-carrier bar upon which the grate baris mounted.

10. A. traveling furnacegrate comprising hollow grate bars for formingthe fuel supporting surfaceof the grate, fixed air inlet and outletconduits extending along the grate, hollow members extending across thegrate "and providing airinlet and outlet compartments in communicationwith said conduits, and connections for supporting said grate bars onsald hollowmembers and mcludmg conduits for establishing communicationbetween the'cavities of the grate bars and said compartments so that airmay flow from said inlet conduit through said inlet compartment and saidgrate bars to cool the said grate bars and be discharged therefromthrough said outlet compartment and outlet conduit.

In witness whereof, I have hereunto signed my name this 26th day ofFebruary, 1929.

ALFRED WILLIAM BENN IS.

